Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
  • H04B1/40—Circuits
  • H04B1/54—Circuits using the same frequency for two directions of communication
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
  • H04B1/40—Circuits
  • H04B1/54—Circuits using the same frequency for two directions of communication
  • H04B1/56—Circuits using the same frequency for two directions of communication with provision for simultaneous communication in two directions
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/14—Two-way operation using the same type of signal, i.e. duplex

Definitions

• the present technology generally relates to radio communications, particularly to a radio network entity for improving filtering performance in a time division duplexing radio communication system and to the method thereof.
• 3 GPP are the most widely deployed in the world.
• a new step being studied and developed in 3 GPP is an evolution of 3G into an evolved radio access technology referred to as Long-Term Evolution (LTE).
• LTE Long-Term Evolution
• different modes of communication can be used for radio nodes in a cellular network, such as Frequency Division Duplex (FDD), Time Division Duplex (TDD) and half duplex.
• FDD Frequency Division Duplex
• TDD Time Division Duplex
• half duplex half duplex.
• the uplink and downlink communications between a radio base station and a user equipment use the same frequency channel (i.e., carrier) but different time slots to separate receiving and transmitting, i.e. receiving and transmitting take place in different, non-overlapping time slots.
• frequency channel i.e., carrier
• the radio network entity could be a user equipment, or a radio base station in a TDD radio communication system.
• the ratio network entity could be a part, internal, or external to (and connected to with a wired connection) a user equipment or a radio base station in a TDD radio communication system.
• a shared TDD filter 27 is used for both transmitting and receiving signals.
• filtering requirements for transmitting and receiving signals are different, and the filtering requirement may vary according to different scenarios.
• worse case of out-of-band attenuations need to be considered, which causes that the filter insertion loss is increased, and unnecessary system performance degradation is resulted.
• a radio network entity for improving filtering performance in a time division duplexing, TDD, radio communication system, comprising: a first filter, which is configured to perform a first type of filtering for a signal to be transmitted to, or received from a device in the radio communication system through a radio interface, with a common filtering requirement for transmitting and receiving fulfilled, a second filter, which is configured to perform a second type of filtering for the signal to be transmitted to the device, with additional filtering requirement for transmitting besides the common filtering requirement fulfilled; and a third filter, which is configured to perform a third type of filtering for the signal received from the device, with additional filtering requirement for receiving besides the common filtering requirement fulfilled.
• a method for a radio network entity for improving filtering performance in a time division duplexing, TDD, radio communication system comprising: performing a second type of filtering for a signal to be transmitted to a device in the radio communication system through a radio interface, with additional filtering requirement for transmitting besides a common filtering requirement for transmitting and receiving fulfilled; and performing a first type of filtering for the signal to be transmitted to, or a signal received from a device in the radio communication system through a radio interface, with the common filtering requirement for transmitting and receiving fulfilled.
• the first filter and the second filter constitute a separate transmitting filter
• the first filter and the third filter constitute a separate receiving filter.
• the three filters do not have to be positioned together, and may be dispersed to be more space efficient.
• the transmitting filter can get better power handling performance if less attenuation is needed compared with the prior art TDD filter.
• Fig. 1 illustrates a schematic view of the environment in which embodiments are implemented
• Fig. 2 illustrates a block diagram of a radio network entity for TDD communication in the prior art
• Fig. 3 illustrates attenuation allocations for the radio network entity for TDD communication in the prior art
• Fig. 4 illustrates a block diagram of a radio network entity for TDD communication in accordance with some embodiments of the present invention
• Fig. 5 illustrates attenuation allocations for the radio network entity for TDD communication in accordance with other embodiments of the present invention
• Fig. 6 illustrates a block diagram of a radio network entity for TDD communication in accordance with other embodiments of the present invention.
• Fig. 7 illustrates part of a block diagram of a radio network entity for TDD communication in accordance with one embodiment of the present invention
• Fig. 8 illustrates part of a block diagram of a radio network entity for TDD communication in accordance with another embodiment of the present invention?
• Fig. 9 illustrates a flowchart of a method performed in a radio network entity for TDD communication in accordance with embodiments of the present invention.
• Fig. 1 illustrates a schematic view of the environment in which embodiments are implemented.
• a TDD radio communication system 100 includes a plurality of radio base stations (RBSs) 101.
• RBSs radio base stations
• connections between RBSs 101 may be implemented in a wired or wireless way, or combination thereof.
• a radio base station 101 is sometimes also referred to in the art as a base station, a macro base station, a femto base stations, a node B, or B-node, an eNode B, etc., besides, also other transceivers or wireless communication stations used to communicate with the user equipment (UE) 102.
• UE user equipment
• each RBS 101 is shown as serving one cell.
• Each cell is represented by a circle which surrounds the respective RBS 101. It will be appreciated by those skilled in the art, however, that an RBS 101 may serve for communicating across the air interface for more than one cell. For example, two cells may utilize resources situated at the same RBS site.
• a UE such as the UE 102 shown in Fig. 1 , communicates with one or more cell(s) or one or more RBS(s) 102 over a radio or an air interface.
• cell(s) or one or more RBS(s) 102 For simplicity and clarity, there are sets of 1 , 2, 3, and 4 UE(s), each in a cell respectively. It will be appreciated that different numbers of UEs may be served by a cell and the numbers UEs served by different cells need not to be identical.
• UE may indicate all forms of devices enabled to communicate via a communication network, such as mobile telephones ("cellular” telephones) and laptops with mobile termination, and thus can be, for example, portable, pocket, hand-held devices, such as mobile phones, smart phones, personal digital assistants (PDA); computer-included devices, such as desktops, laptops; vehicles, or other devices, such as meters, household appliances, medical appliances, multimedia devices, etc., which communicate voice and/or data with radio access network.
• PDA personal digital assistants
• computer-included devices such as desktops, laptops
• vehicles or other devices, such as meters, household appliances, medical appliances, multimedia devices, etc., which communicate voice and/or data with radio access network.
• the uplink and downlink communication between an RBS and a UE use the same frequency channel (i.e., carrier) but different time slots to separate receiving and transmitting, i.e. receiving and transmitting take place in different, non-overlapping time slots.
• frequency channel i.e., carrier
• the radio network entity could be a UE 102, or an RBS 101 in a TDD radio communication system 100.
• the ratio network entity could be a part, internal, or external to (and connected to with a wired connection) a UE 102 or an RBS 101 in a TDD radio communication system.
• a shared TDD filter 27 is configured for both transmitting and receiving signals to or from a device in the TDD radio communication system 100.
• the radio network entity comprises an antenna 28, also known as an aerial, or a transducer designed to transmit or receive electromagnetic (e.g.
• the radio network entity further comprises a circulator 26, which plays a role to separate a transmitting path and a receiving path, a TDD switch 25, which is configured to route transmitting leakage signals to 50 ohm resistor 29 and then to the ground in transmitting slots and connect to a receiver (RX) 22 in receiving slots, a power amplifier (PA) 23, which is configured to perform power amplifying for signals to be transmitted through the antenna 28, a low noise amplifier (LNA) 24, which is configured to perform power amplifying for signals received through the antenna 28, particularly to boost the desired signal power while adding as little noise and distortion as possible, a transmitter (TX) 21 , which is configured to configure the signal for proper transmission according to radio communication protocols in the TDD radio communication system 100, and the RX 22 for proper receiving according to radio communication protocols in the TDD radio communication system 100.
• the part between the antenna 28 and RX 22 is referred to as a receiver front end, and the part between the antenna 28 and the TX 21
• spurious emission elimination at a higher side of the operation band needs to be mainly considered, and attenuation required at a lower side of the operation band is relatively more relaxed.
• blocking elimination requires tougher filter attenuation at the lower side of the operation band and attenuation required at the higher side is relatively more relaxed.
• a dot dashed line stands for passband of filtering requirement in frequency domain for transmitting signals
• a dotted line stands for passband of filtering requirement in frequency domain for receiving signals.
• spurious emission elimination at lower side of operation band needs to be mainly considered, and attenuation required at higher side of operation band is relatively more relaxed, and for receiving signals, blocking elimination requires tougher filter attenuation at the higher side of the operation band and attenuation required at the lower side is relatively more relaxed.
• the filtering requirement for receiving signals at the higher side of the operation band as shown in Fig 3 is designed to meet all possible critical blocking elimination requirements, the blocking may being caused by interferences from other sources due to co-location or co-existence. But for some or even most TDD radio communications, blocking interferences due to co-location or co-existence may not exist, which means the attenuation at higher side of the operation band for filtering requirement for receiving signals shown in Fig. 3 is not always required.
• Fig. 4 illustrates a block diagram of a radio network entity for TDD communication in accordance with some embodiments of the present invention.
• the radio network entity could be a UE, or an RBS in a TDD radio communication system.
• the ratio network entity could be a part, internal, or external to (and connected to with preferably a wired connection) a UE 102 or an RBS 101 in a TDD radio communication system 100.
• the radio network entity comprises an antenna 28, a circulator 26, a dual path switch 45, a power amplifier (PA) 23, a low noise amplifier (LNA) 24, a transmitter 21 , a receiver 22, filteri 42, filter 2 43, and filter 3 44.
• PA power amplifier
• LNA low noise amplifier
• the antenna 28 is a transducer configured to transmit or receive signals in the form of electromagnetic waves, transducing from electrical signals to electromagnetic waves, or vice versa. In most cases, the antenna 28 is shared for both transmitting and receiving according to the reciprocity principle of antenna. However, it does not exclude a scenario that two separate antennas are configured for transmitting and receiving respectively.
• the circulator 26 is configured to plays a role to separate a transmitting path and a receiving path within the radio network entity, and could be replaced by a switch to fulfill similar functions.
• the switch 45 is configured to route transmitting leakage signals to the 50 ohm resistor 29 and then to the ground in transmitting slots and connect to the receiver (RX) 22 in receiving slots.
• the power amplifier (PA) 23 is configured to perform power amplifying for signals to be transmitted through the antenna 28.
• the low noise amplifier (LNA) 24 is configured to perform power amplifying for signals received through the antenna 28, particularly to boost the desired signal power while adding as little noise and distortion as possible.
• the transmitter 21 is configured to configure the signal for proper transmission according to radio communication protocols in the TDD radio communication system 100.
• the receiver 22 is configured for proper receiving according to radio communication protocols in the TDD radio communication system 100. It is noted that the antenna 28, the circulator 26, the dual path switch 45, the PA 23, the LNA 24, the transmitter 21 and the receiver 22 are applicable to conventional rules, and those elements could easily be bought on the market.
• the filteri 42 is configured to perform a first type of filtering for a signal to be transmitted to, or received from a device in the TDD radio communication system 100 through the antenna 28, with a common filtering requirement for transmitting and receiving fulfilled.
• Filter 43 is configured to perform a second type of filtering for signals to be transmitted to the device, with additional filtering requirement for transmitting besides the common filtering requirement fulfilled.
• Filters 44 is configured to perform a third type of filtering for signal received from the device, with additional filtering requirement for receiving besides the common filtering requirement fulfilled.
• the device could be the UE 102 or the RBS 101 , and in the hierarchically structured radio communication system shown in Fig.
• the device herein when the radio network entity is, or internally or externally belongs to the UE 102, the device herein is the RBS 101 and when the radio network entity is, or internally or externally belongs to the RBS 101 , the device herein is the UE 102.
• a signal to be transmitted through the antenna 28 to a device in the radio communication system is generated in the TX 21 , and it will then go in order through PA 23, the filter 2 43, the circulator 26, the filter i 42 till the antenna 28 and be transduced into electromagnetic waves in the air. Meanwhile, the switch 45 will route a leakage signal as a part of the signal to be transmitted to the 50 ohm resistor 29 and then to the ground.
• a signal is received through the antenna 28 and will go in order through the filteri 42, the circulator 26, the switch 45, the filter 3 44, the LNA 24 till the RX 22.
• filters 44 only carries low power radio frequency signals, so it does not need to fulfill high power handling and passive intermodulation requirements.
• filter 3 44 has more flexibility on implementation, for example, in one scenario, high Q value is the main concern, thus flexible cavity size can be implemented to ensure the Q value; in another scenario, miniaturization is the main concern, then more types of resonators such as microwave planar circuit resonator, which can be realized on PCB can be used, which will contribute much to miniaturization of filter 3 44 for sure with the penalty on the lower Q value of the resonator; In still another scenario, medium size and medium Q value are required, and the implementation thereof could thus be designed. It is similar for filter 43.
• Q value refers to a measurement of a resonant system's relative bandwidth.
• Q value is a dimensionless parameter that describes how under-damped an oscillator or resonator is, or equivalently, characterizes a resonator's bandwidth relative to its center frequency.
• High-Q filter would do a better job of filtering out signals that lie nearby on the intended band and have lower insersion loss.
• switch 45 could be replaced by a proper set of voltage control diode to fulfill similar functions.
• the signal received through the antenna 28 may go in order through the filter ! 42, circulator 26, the LNA 24, the switch 45, the filter 3 44 till the RX 22.
• the LNA 24 is positioned between the circulator 26 and the switch 45 (not shown).
• the LNA 24 It is advantageous to have the LNA 24 positioned this way, and this embodiment can improve noise figure of receiverfront end of the radio network entity. It will be appreciated by those skilled in the art that the LNA 24 could be blocked by strong signals, such as strong interferences from other sources due to co-location or co-existence, therefore, the performance of the LNA 24 in this embodiment depends on out-of-band rejection of filter i.
• Fig. 5 illustrates attenuation allocations for the radio network entity for TDD communication in accordance with embodiments of the present invention.
• a common filter i.e., filteri 42 needs to meet basic attenuations for both the transmitting path and the receiving path, which are attenuation Attl at frequency fl and attenuation Att4 at frequency f4.
• Additional transmitting filter i.e. filter 2 43 needs to provide further attenuation needed for transmitting path only, which is attenuation ATT_tx2 at frequency f3.
• ATT_tx2 is Att3 minus common filter attention ATT txl at frequency f3.
• Additional receiving filter, i.e. filter 3 44 needs to provide further attenuation needed for receiving path only, which is attenuation ATT_rx3 at frequency f2.
• ATT_rx3 is Att2 minus common filter attention ATT rxl at frequency f2.
• the attenuation requirement is in positive relation to the needed pole number of the filter.
• the unnecessary poles are waived, in other words, the needed pole number is reduced, and the insertion loss caused by unnecessary poles is thus avoided.
• Fig. 6 illustrates a block diagram of a radio network entity for TDD communication in accordance with other embodiments of the present invention.
• the bypasser 61 is configured at least based on a connection between a dual path switch, switch 2 62 and a triple path switch, switchi 63. Therefore there are two routes for the received signals coming out from the circulator 26.
• One is a filtering route, in which the received signals coming out from the circulator 26 will route in order though switchi 63, filter 3 44, switch 2 62 to the LNA 24.
• the other is a bypass route, in which the received signals coming out from the circulator 26 will route in order though switchi 63, switch 2 62 to the LNA 24, bypassing filter 3 44.
• the radio network entity further comprises an interference detector 65 coupled to the antenna 28, configured to detect interferences received, and a controller 64 configured to control operation of the bypasser 61 , i.e. , to control status of switchi 63 and switch 2 62 based on the detected interferences.
• the interference detector 65 further comprises a detection filter 66 and a power detector 67.
• the detection filter 66 is configured to couple to the antenna 28 and obtain the interferences when the antenna 28 is not performing transmission
• the power detector 67 is configured to determine power level of the interferences.
• the controller 64 is further configured to switch between the bypass route and the filtering route, i.e. , to activate the bypass route if the power level of the interferences is lower than a predetermined threshold, and activate the filtering route if the power level of the interferences is not lower than the predetermined threshold, by controlling status of switchi 63 and switch 2 62.
• the radio network entity further comprises a gain compensator 68, which is configured to perform gain compensation between the bypass route and the filtering route.
• the controller 64 is further configured to notify the gain compensator 68 of the activating of the bypass route and the filtering route, i.e. , begin and end time information of transmission through the bypass route and that through the filtering route.
• the signal received through the antenna 28 may go in order through the filteri 42, the circulator 26, the LNA 24, the switchi 63, then the filter 3 44, the switch 2 62 to the RX 22, or that the signal received through the antenna 28 may go in order through the circulator 26, the LNA 24, switchi 63, then directly switch 2 62 bypassing filter 3 44 to the RX 22.
• the LNA 24 is positioned between the circulator 26 and switchi 63, as is shown in fig. 7.
• the LNA 24 It is advantageous to have the LNA 24 positioned this way, and this embodiment can improve noise figure of receiver front end of the radio network entity. It will be appreciated by those skilled in the art that the LNA 24 could be blocked by strong signals, such as strong interferences from other sources due to co-location or co-existence, therefore, the performance of the LNA 24 in this embodiment depends on out-of-band rejection of filteri.
• V ctr i 81 acts as a switch to activate or deactivate the bypass route.
• V ctr2 82 and V ctr 3 83 act as a switch to activate or deactivate the filtering route.
• the first filter filter ! 42 and the second filter filter 2 43 constitute a separate transmitting filter
• the first filter filter ! 42 and the third filter filter 3 44 constitute a separate receiving filter.
• the three filters filteri 42, filter 2 43 and filter 3 44 do not have to be positioned together, and may be dispersed to be more space efficient.
• the three filters, all together, cost fewer than just one shared filter in the prior art due to decreased power handling requirement.
• Variance of the receiving filter could be applied according to an interference signal power level, by activating and bypassing the third filter. More flexibility for the third filter filters 44 implementation could be achieved, because the third filter filter 3 44 is released from power handling and passive intermodulation requirements. The transmitting filter can get better power handling performance if less attenuation is needed compared with the prior art TDD filter.
• Fig. 9 illustrates a flowchart of a method performed in a radio network entity for TDD communication in accordance with embodiments of the present invention.
• TDD radio communication system 100 through the antenna 28 arrives from the TX 21 and goes through the PA 23, a second type of filtering is performed for it, with additional filtering requirement for transmitting besides a common filtering requirement for transmitting and receiving fulfilled at step 918, following the passband of additional transmitting filter in Fig. 5, and then a first type of filtering is performed for it, with the common filtering requirement for transmitting and receiving fulfilled at step 920, following the passband of common filter in Fig. 5.
• a first type of filtering is performed for the signal, with the common filtering requirement for transmitting and receiving fulfilled at step 902, following the passband of common filter in Fig. 5.
• the interferences from other sources due to co-location or co-existence are obtained at step 906.
• the interferences could be obtained anytime when the antenna 28 is not performing transmission, including at idle periods and guard periods.
• power level of the interferences is determined. If the power level is determined not lower than a predetermined threshold at step 910, a third type of filtering with additional filtering requirement for receiving besides the common filtering requirement fulfilled is performed for the signal received at step 912, following the passband of additional receiving filter in Fig. 5.
• time information of performing or not performing the third type of filtering is notified for the purpose of gain compensation at step 914, and then the gain compensation between signals with and without the third type of filtering being performed could be performed at step 916.
• low noise amplifying is performed for the signal received at step 904 following step 902. In another example, low noise amplifying is performed for the signal received right before it being processed by a receiver.
• steps 906, 908, 910, 914 and 916 are not necessary.
• the first filter filter ! 42 and the second filter filter 2 43 constitute a separate transmitting filter
• the first filter filter ! 42 and the third filter filter 3 44 constitute a separate receiving filter.
• the three filters filter ! 42, filter 2 43 and filter 3 44 do not have to be positioned together, and may be dispersed to be more space efficient.
• the three filters, all together, cost fewer than just one shared filter in the prior art due to decreased power handling requirement.
• IL insertion loss
• Variance of the receiving filter could be applied according to an interference signal power level, by activating and bypassing the third filter. More flexibility for the third filter filters 44 implementation could be achieved, because the third filter filter 3 44 is released from power handling and passive intermodulation requirements. The transmitting filter can get better power handling performance if less attenuation is needed compared with the prior art TDD filter.

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• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Transceivers (AREA)
• Mobile Radio Communication Systems (AREA)

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• 2014
  • 2014-06-16 WO PCT/CN2014/079959 patent/WO2015192297A1/en active Application Filing
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  • 2014-06-16 RU RU2017101082A patent/RU2663377C2/ru active
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  • 2014-06-16 EP EP14895128.8A patent/EP3155868B1/en active Active
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• 2019
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